This proposal seeks to elucidate the role that proteolytic enzymes (with major emphasis on collagenolytic enzymes) might play in the ability of tumors to invade normal tissue and to metastasize to other parts of the body, and has as its ultimate objective the design of specific inhibitors which will suppress malignant growth. In order to accomplish this objective, the following approaches will be taken: 1) To determine whether there are any/or qualitative differences in collagenolytic activity between primary and metastatic tumors (human), 2) to isolate and characterize the collagenolytic enzymes, 3) to explore various means whereby the activity of these enzymes could be inhibited in vitro and their biosynthesis curtailed in vivo by hormonal treatment, and 4) to test the effectiveness of such agents in the inhibition of tumor growth and metastasis in animal model systems.